The present invention relates to a device for unlocking doors of a motor vehicle in the event of a malfunction.
Such a device (lock) for the unlocking of doors of a motor vehicle in the event of a malfunction is known from European Patent Application EP 0 589 158 A1. In addition to the operation of the lock described therein by activated switches which detect the actuating of the door handle and connect a setting drive which moves a locking pawl from a locking position which locks the rotary latch into an open position which releases the rotary latch, measures have been taken for the event of a malfunction. An actuator of the drive can, for instance, be displaced by a crash sensor or, in the event of a malfunction, by a sensor which detects the malfunction, in such a manner that a coupling element or the setting drive enters into an active position in which transmission elements permit an unlocking of the pawl by the actuating of a door handle. However, this has the disadvantage that the setting drive is used both for the normal case and in the event of a malfunction and therefore does not operate reliably in the event of a malfunction. If the crash sensor detects a predetermined deceleration of the vehicle the microswitches are placed in active condition so that the lock can still be actuated after actuation of a door handle. However, if the current supply fails or if the central electronic system of the car is defective, the electric actuation of the lock also fails. Then, however, it is no longer possible, even by corresponding control of the setting drive, for a swing lever to swing into an active position in which the door handle moves the pawl mechanically into its unlocked position via a pull cable and a swing lever. Therefore the lock cannot be opened either electrically or mechanically, which is extremely unsatisfactory from the standpoint of safety.
The connecting of an additional battery requires an evaluation and switch logic, which itself is subject to breakdown and is cost-intensive, as is the additional battery.
A known mechanically operating lock does not have an electrically operable setting drive so that in this case no measures are provided for actuating the lock in the event of a malfunction.